Biology 101: Meiosis
by theinspired
Summary: During The Doctor's Daughter, the Doctor gets a little carried away with a science lesson. This was a biology assignment. I had to write a story about meiosis using certain vocabulary. Of course, I had to tie it in to Doctor Who. Hope you like it!


**I realize that I never refer to Jenny by her name. But! I have good reason. This scene takes place before Donna gives her the name, so she's still nameless at this point. Yup! So...enjoy!**

"Hi, Dad."

Donna blinked at the strange blond woman, who was now smiling brilliantly at the Doctor. It took her mind a moment to register the proper noun she had just called the Time Lord.

"Did she just call you '_Dad_'?" Donna asked incredulously.

The Doctor never broke the bewildered gaze he had on the blond before him, "I believe so...yeah."

"And just how exactly is _she_ your daughter? She just stepped out of a machine, for Pete's sake!"

"Progenation machine." He said, finally glancing at his companion.

"What?"

"That-" He gestured to the box-like appliance the woman had stepped out of. "-is a progenation machine. Progenation involves taking a sample of diploid cells, splitting them into haploids, then recombining them in a different arrangement and...grow. Very fast, apparently." He commented, still studying his daughter.

"So...what you're saying is...you're her only parent?" Donna asked, barely picking out his words from his light-speed ramble.

"Yeah..." He took note of her confused expression. "Do you know about meiosis?"

Her confusion quickly turned to anger. "Should I?"

"See," He began, taking her comment as a no. "Meiosis is a cell division that is used in sexual reproduction. It produces gametes, such as the sperm and the egg, which are used to create a zygote."

Donna blinked once again; fire burning in her eyes, "_What_ on Earth would make you think I _wanted_ to know that?"

"Donna," He scolded. "We're not on Earth. We're on Messaline!"

A nasty retort didn't come to mind, so she settled for glaring at him.

"Anyway," He sighed. "Diploids and haploids..." He stared off into the middle distance for a moment, concoction a suitable explanation, then spoke. "Diploid cells have two sets of chromosomes. They also contain the characteristic number of chromosomes for a species. For example, humans have-"

"46 chromosomes." Donna interjected tiredly, giving up on talking him out of the lecture.

"-46... Yes! That's right. Good, Donna. And a haploid cell has half the chromosomes of a diploid cell. In humans-"

"Half of 46 is 23." She could feel sleep nagging at her already.

"Exactly. Now, if you get tired of saying 'diploid' (which, I don't know why you would, it's rather fun to say), you can say 2N. It's just an abbreviation; completely interchangeable. Same goes for 'haploid', only you'd say just plain ole N. They both stand for the number of diploid and haploid cells, respectively." He paused, sucking in a few breaths of musty air. "Now, meiosis. It's-"

"Sounds a lot like _mi_tosis to me." Donna said, finding sudden interest in her clothing.

"Actually, meiosis is very similar to mitosis, only you end up with two haploid cells. You humans are very indomitable. The whole point-"

"Is that a complement?" She raised an eyebrow incredulously.

"-is," He continued, not acknowledging her question. "to provide gene diversity to the population. The chromosomes do this by crossing-over during the first telophase. Pieces of-"

"There's _more _than one telophase?" Suddenly, Donna seemed interested.

"-the homologs-" He stopped himself to address her query. "Yes. Meiosis has two divisions: I and II. At the end of it all, you get four gametes."

"Oh."

"Yep. Now...where was I?" He paused. "Right! Crossing-over! The homologous chromosomes, chromosomes that have the same type of gene in the same location, join together. The two pairs of sister chromatids-"

Donna frowned, "Chromatids?"

"Condensed chromatin." He answered quickly, then continued with his lesson. "The chromatids join together to form a tetrad. Then, they exchange genes. After that, the cell goes through Meiosis I. Anaphase, Metaphase, Telophase, and Cytokinesis. At the end, there's two haploid cells. These cells go through Meiosis II (Prophase, Anaphase, Metaphase, and so on). Finally, four gametes are formed. In progenation, they would be recombined and grown into a generated anomaly." He pointed to the woman.

"Don't point!" Donna scolded. "It's rude."

He fixed her with a steely glare, "Usually though, the egg has to be fertilized by th-"

"Oi!"

The Doctor became confused, "What?"

"I've already had 'the Talk' once in my life. I don't need it again,_ especially_ not from you."

"I wasn't-"

Donna held up a hand. "Thanks for the lesson, Doctor. Never bring this up again."

"But-"

"_Never_."

Seeing her burning glare, he sighed. "Fine."

**Cut! Hope you enjoyed the science lesson! Please review. Constructive criticism is always appreciated.**

**Side note: If you enjoyed this, you might also enjoy Hijacked. It will be the first in my own personal season with David Tennant! 'Cause we can always use a little more Ten! So...let me know in a review and/or PM if you'd like to get a sneak peak. *wink, wink*  
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